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关键词： Quantum spin liquid   Tensor network state   Frustrated magnets   Deconfined quantum critical point  

摘要： The nature of the zero-temperature phase diagram of the spin-1/2 J_(1)-J_(2)Heisenberg model on a square lattice has been debated in the past three decades,and it remains one of the fundamental problems unsettled in the study of quantum many-body *** using the state-of-the-art tensor network method,specifically,the finite projected entangled pair state(PEPS)algorithm,to simulate the global phase diagram of the J_(1)-J_(2)Heisenberg model up to 24×24 sites,we provide very solid evidences to show that the nature of the intermediate nonmagnetic phase is a gapless quantum spin liquid(QSL),whose spin-spin and dimer-dimer correlations both decay with a power law *** also exists a valence-bond solid(VBS)phase in a very narrow region 0.56■J_(2)/J_(1)≤0.61 before the system enters the well known collinear antiferromagnetic *** stress that we make the first detailed comparison between the results of PEPS and the well-established density matrix renormalization group(DMRG)method through one-to-one direct benchmark for small system sizes,and thus give rise to a very solid PEPS calculation beyond *** numerical evidences explicitly demonstrate the huge power of PEPS for highly frustrated spin ***,an effective field theory is also proposed to understand the physical nature of the discovered gapless QSL and its relation to deconfined quantum critical point(DQCP).

关键词： 量子力学   量子力学  

ISBN: (纸本)9787512437760

摘要： 本书以发展的眼光看待通信技术，介绍一些传统保密通信的困境，以及量子通信的重要意义和发展战略，将量子通信的主要协议和方案择重点进行讲解，并介绍量子通信系统实现过程中的关键技术、部分攻击和防御方案，以及量子通信网络的建设情况，以典型量子通信系统为例，概述了相关系统的构建。

摘要： Robust, high-fidelity readout is central to quantum device performance. Overcoming poor readout is therefore an increasingly urgent challenge for devices based on solid-state spin defects, particularly given their rapid adoption in quantum sensing, quantum information, and tests of fundamental physics. However, in spite of experimental progress in specific systems, solid-state spin sensors still lack a universal technique for high-fidelity readout. One leading research avenue is to engineer state-of-the-art microwave delivery systems which improve the coherent control of large spin ensembles as they are manipulated for readout. Another is to develop novel readout techniques that go beyond measuring optical fluorescence signals, which are often difficult to detect, and unique only to some solid-state spin systems. In this thesis, I discuss these two approaches, and begin by designing a three dimensional microwave resonator that overcomes the many shortcomings of conventional microwave delivery systems, which limit the readout fidelity of devices employing large spin systems. Next, I demonstrate a novel readout technique that provides high-fidelity, room-temperature readout of an ensemble of nitrogen-vacancy centers via strong coupling to a dielectric microwave cavity. This strong collective interaction allows the spin ensemble’s microwave transition to be probed directly, thereby overcoming the optical photon shot noise limitations of conventional fluorescence readout. Applying this technique to magnetometry, I first build a proof-of-concept magnetometer with the capability of measuring magnetic fields along a single vector axis, with a sensitivity better than the optical shot noise limit of the system. I then expand on the initial demonstration, by building a prototype capable of measuring three-dimensional dynamic vector fields with high sensitivity. While the current device performance is limited by technical noise, the method promises what has long been elusive f

关键词： 会计报表  

ISBN: (纸本)9787115587657

摘要： 本书共10章，首先对利润表、资产负债表、现金流量表的常见问题进行讲解，帮助读者正确认识三大报表。然后从不同视角出发，讲解了各视角中需要关注的财报侧重点，如投资者如何判断企业盈利与发展能力、债权人如何判断偿债与营运能力、管理者如何借助财报调整企业战略发展方向并发现内控舞弊、四大行业的财报各自的特点等。最后，从识别财报造假为结束，夯实对财报认知与分析方法。

关键词： 会计报表-会计分析  

ISBN: (纸本)9787115587657

摘要： 财务报表能帮助管理者调整企业战略方向、决策投融资，也能帮助投资者、债权人判断企业价值、掌握企业经营情况。本书共10章，先对利润表、资产负债表、现金流量表的常见问题用生动的语言、形象的比喻进行讲解，来帮助读者正确认识三大报表，快速走进财报的大门。然后从不同视角出发，讲解了各视角中需要关注的财报侧重点，如投资者如何判断企业盈利与发展能力、债权人如何判断偿债与营运能力、管理者如何借助财报调整企业战略发展方向并发现内控舞弊、四大行业的财报各自的特点等，能满足不同新手的多角度需求。之后，从识别财报造假为结束，夯实财报认知与分析方法。本书用情景案例轻松“翻译”了企业的经营活动，非常通俗易懂。其案例丰富、实用性强，适合投资者、债权人、管理者作为财报学习的入门读物。不懂财务的人也能轻松读懂财报。

摘要： Competing interactions between strong spin-orbit coupling (SOC) and electron correlations have recently led to widespread studies of various emergent novel quan- tum phases. Recent interest has been placed in Mott insulators with strong SOC, particularly those containing 5d transition-metal ions where SOC and electron cor- relations can be of comparable magnitude. In this thesis, we present a comprehen- sive study on the effects of charge doping on the double perovskite Ba 2 NaOsO 6, a Mott insulator with both strong electron correlations and SOC. Specifically, we re- port zero-field systematic muon spin relaxation (µSR), magnetization, and nuclear magnetic resonance (NMR) studies of the magnetic and structural phase evolution as a function of charge doping of Ba 2 Na x Ca 1−x OsO 6 through the Na + /Ca ++ partial substitution for 0 ≤ x ≤ 1. Similar to Ba 2 NaOsO 6, we find the existence of an intermediate temperature re- gion with orthorhombic electric field gradient (EFG) symmetry before the onset of magnetic ordering in Ba 2 Na x Ca 1−x OsO 6, indicating a breaking local point symmetry (BLPS) phase. In the low temperature magnetic state, the ferromagnetic moment component present in Ba 2 NaOsO 6 is almost completely suppressed when x ≥ 0.125. Under a canted antiferromagnetic (AFM) model of Ba 2 NaOsO 6, a staggered angle around 86(1) degrees was found for 0.125 ≤ x ≤ 0.9, implying a collinear AFM state, while Jahn-Teller type structural transitions support the existence of possible quadrupolar moments. Moreover, the magnetic insulating state is preserved across all doping concentrations despite the introduction of extra electrons into the system. By constructing a magnetic and structural phase diagram as a function of charge doping, our work sheds light on the effect of electronic correlation strength in the complex interplay of magnetic, structural, and lattice degrees of freedom in the interesting 5d 1 and 5d 2 Mott insulator systems. Towards the end, the desig

关键词： Dirichlet eigenvalues   Fractional Laplacian   Berezin-Li-Yau method   Mixed nonlocal operator   Mixed   fractional Laplacian  

摘要： Our purpose in this paper is to study of the eigenvalues {lambda(i)(mu)}(i) of the Dirichlet problem (-Delta)(s1)u=lambda((-Delta)(s2)u + mu u) in Omega, u = 0 in R-N \ Omega, where 0 < s(2) < s(1) < 1, N 2(s1) and (-Delta)(s) is the fractional Laplacian operator defined in the principle value sense. We first show the existence of a sequence of eigenvalues, which approaches infinity. Secondly we provide a Berezin-Li-Yau type lower bound for the sum of the eigenvalues of the above problem. Furthermore, using a self-contained and novel method, we establish an upper bound for the sum of eigenvalues of the problem under study. (c) 2022 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： 运动表象训练   高校   足球教学   应用  

摘要： 随着国家于校园足球事业发展的重视,越来越多的学校开始注重对学生足球运动技能培养.高校承担着为国家培养人才的重任,在新教学理念的指导下,学校方面要积极开展足球教学,让学生在学习足球技能的过程中提升运动意识,不断促进学生体质健康水平的提升等.表象训练教学法是运动训练当中比较常用的方法,其高校足球教学中的应用,不仅让学生在短时间内有效地掌握到相应的足球技术要领,还能充分调动学生对于足球运动的兴趣,从而全面提升学生的足球运动水平,为此,文章采用文献资料法等,就对运动表象训练在高校足球教学中的应用开展研究.

关键词： 量子   量子纠缠   量子力学  

摘要： 如果将物体分散到无法分析的单位,例如光子,人们就称这样的粒子为量子,而量子纠缠则是指利用某种方法产生几种相关联的量子,不管这几种量子各自彼此间距有多远,内部也并不是同一个介质,只是其中某个量子态的改变将会影响到另一种量子的态.文本主要讲述了量子的特性和量子纠缠的现象,量子纠缠在生物界的存在现象,以及量子纠缠在计算、通讯和军事领域的应用情况,最后探讨量子纠缠可能形成的原因.